Large diameter cylindrical rotary kilns are frequently used in various industrial processes, such as the calcining of lime, cement and diatomaceous earth, the production of steel pellets, and other manufacturing operations. Conventional kilns consist of a cylindrical steel outer shell with an internal lining of refractory brick. Refractory bricks are placed circumferentially within rows in the kiln. During initial placement or replacement of a brick lining, it is necessary to support bricks in the overhead portion of the kiln until all the bricks in a circumferential row are securely in place, at which time the bricks become self-supporting. Brick support rings have been developed for this purpose.
To line a kiln using a bricking ring, a row of bricks is first placed in the lower half of the kiln, followed by a build-up of the bricks around the upper circumferential half of the kiln, with the bricking ring providing support to the bricks in the upper half as they are placed. A conventional bricking ring that functions in this manner is disclosed by U.S. Pat. No. 3,466,883, and comprises a rigid semicircular ring that is supported by a lower frame within the kiln. The ring includes a plurality of radially-spaced pneumatic cylinders, each pneumatic cylinder having a piston rod extending radially outward therefrom and terminating in a brick support foot. As bricks are stacked within the upper half of the kiln, the pneumatic cylinders are correspondingly activated in sequence to hold the bricks until a complete circle of bricks has been positioned securely in place, at which point the ring may be removed to begin placement of the next course of bricks. While this bricking ring functions satisfactorily, it can be used only to line a kiln having a certain diameter due to the rigid nature of the ring. The only size variation accommodated by the ring is that afforded by limiting the extension of the pneumatic cylinder rods. However, a variety of standard kiln sizes exist, necessitating a kiln lining contreactor to maintain a number of different size rings of this conventional design in order to service a broad base of kilns.
Conventional rigid rings of this type are also ill-suited for use in kilns which vary in diameter over their length. Additionally, in recent years kilns have been manufactured or refurbished to include a layer of insulating brick between the outer shell of the kiln and the inner refractory brick to conserve energy. Unfortunately, the thickness of the insulation bricks is sufficient to render many conventional rings too small for use in the size kilns for which the rings were originally designed.
U.S. Pat. No. 4,450,666 discloses a size-adjustable bricking ring that is more adaptable than conventional rings. The ring consists of a sequence of arcuate sections that are pivotally joined at their ends to form a semicircular ring. The ends of the semicircular ring are joined to a transverse telescoping member of a scaffold support. Each pivotal joint between ring sections is supported by a telescoping radial member extending from the transverse scaffold member outward to the pivotal joint. To increase the size of the ring, the transverse member of the scaffold is telescoped outwardly and the telescoping radial support members are lengthened accordingly to maintain the semicircular conformation of the ring. The ring further includes two telescoping arcuate end sections to increase the overall arcuate length of the ring. This adjustable ring overcomes the narrow applicability of rigid rings. However, this ring is not well suited for use in the narrow confines of kilns. Using conventional bricking techniques, a worker stands on the scaffold and receives refractory bricks passed under the bricking ring by other workers. This conventional, radially supported adjustable ring does not allow the free passage of workers and bricks under the scaffold due to the presence of the telescoping radial supports. The overall structure is also heavy due to the presence of the radial telescoping supports, making it difficult to move the ring within the kiln to place subsequent rows of brick.